EP0715187B1 - An electrical logging sensor and its method of manufacture - Google Patents

An electrical logging sensor and its method of manufacture Download PDF

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Publication number
EP0715187B1
EP0715187B1 EP95402667A EP95402667A EP0715187B1 EP 0715187 B1 EP0715187 B1 EP 0715187B1 EP 95402667 A EP95402667 A EP 95402667A EP 95402667 A EP95402667 A EP 95402667A EP 0715187 B1 EP0715187 B1 EP 0715187B1
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EP
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Prior art keywords
coating
sensor according
support
insulating
deposited
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EP95402667A
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German (de)
English (en)
French (fr)
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EP0715187A1 (en
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Richard Saenger
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Schlumberger Ltd
Schlumberger Technology BV
Schlumberger Holdings Ltd
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Gemalto Terminals Ltd
Schlumberger Technology BV
Schlumberger NV
Schlumberger Ltd USA
Schlumberger Holdings Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
    • G01V3/18—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation specially adapted for well-logging
    • G01V3/20—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation specially adapted for well-logging operating with propagation of electric current

Definitions

  • the present invention relates to the field of measurement tools suitable for use in borehole equipment for oil prospecting and production.
  • logging instruments in particular electrical or electromagnetic sensors, are lowered into the well for the purpose of taking measurements that enable characterization of the fluids present in the formations and the beds traversed by the borehole as well as determination of the dip of said beds.
  • Figures 1a and 1b are diagrams showing an example of a logging sensor, of the type comprising electrodes on a pad. Such a sensor and its operation are also described in document EP-A-384 823.
  • Figures la and 1b show a pad 3 comprising a stainless steel support 7 covered in a layer 8 of hard rubber in which electrodes 10-22 are embedded.
  • the outside surface 11 of each electrode should normally be flush with the outside surface 13 of the layer of rubber, as in Figure 1b.
  • the pad is designed to be held, during measurement, against the wall of the borehole by means of a system of retractable arms, hinged to a sonde that is lowered down the borehole on an electrical cable, to a depth that may be as much as several kilometers.
  • analysis current I is injected into the formations around electrodes 16, 18, 20, and 22 ( Figure la).
  • the electrode 10 is a guard electrode and it serves to inject focusing current.
  • Electrodes 12-1 and 12-2 are monitoring electrodes and electrodes 14-1 and 14-2 are focusing electrodes through which another focusing current is injected. Detailed operation of the device is described in the above-mentioned document.
  • temperature may be high (as much as 175°C or higher), the pressures encountered are commonly in the range 700 bars to 1400 bars, and the materials may be in contact with aggressive fluids (HCl, H 2 S, etc.).
  • the sensors and their environment are sometimes subjected to mechanical stresses that are very intense.
  • the outside surface is held in rubbing contact against the walls of the borehole, and this may continue over distances that are considerable.
  • some of the surfaces may be worn to a depth of 1.5 mm, whereas to ensure measurement reproducibility, it is necessary to keep maximum wear to no more than about 0.2 mm.
  • resistivity logs are obtained such as that shown in Figure 2.
  • the variations associated with the nature of the beds being logged as illustrated by curve 31 have interference peaks 26, 28, 30, and 32 superposed thereon, which peaks are known "spikes".
  • the origin of such spikes is associated with particles or lumps of matter coming from the formations being logged and which attach to the active surface of the sensor (in this case the electrode 10). When they become detached from said surface, a sudden change in the conductivity of the electrode occurs, and the sensor responds thereto in a manner that gives rise to an interfering spike appearing.
  • This phenomenon is associated with the state and with the nature of the surface of the sensors and with the passivation layer being torn off.
  • Figure 3a is a side view of the sensor while Figure 3b is a half-section on AA'.
  • Reference 21 designates a half-shell constituted by a metal substrate 23 that is cylindrical in shape, and by a rubber coating 25 in which there are received azimuth electrodes 27-1, ..., 27-6 for injecting current, and azimuth monitoring electrodes 29-1, ..., 29-6 situated in the centers of the electrodes 27 and insulated therefrom.
  • Other monitoring electrodes 33 and 35 are disposed at the ends of the device.
  • the electrodes are connected to their electrical supplies by means of wires that are embedded in the rubber 25, and that are collected together at a base 39 welded on the inside face of the substrate 23, which base is extended by a connector 41 that is water and gas-tight.
  • this sensor is inserted in a tubular sonde that is lowered down a borehole at the end of a cable and that is held centered in the borehole.
  • the sensor is designed to be used in a medium where the temperature can be high (up to 175°C) and the pressure can be very large (up to 1400 bars).
  • its outside surfaces are in contact with aggressive fluids (HCl, H 2 S, ..., etc.).
  • aggressive fluids HCl, H 2 S, ..., etc.
  • sensors are difficult and expensive to make insofar as they require numerous components: a substrate, electrodes, a base which needs to be welded, a connector, rubber envelopes, and insulators.
  • UK patent application GB-2 130 380 discloses a drill string electrode structure.
  • European patent application EP-0 327 422 discloses a method to interpret electrical borehole loggings.
  • an electrical measurement sensor according to claim 1.
  • Such sensor is particularly suitable for use in a resistivity logging tool.
  • the invention also provides a method of manufacturing an electrical measurement sensor according to independent claim 23.
  • Figures 4a and 4b A first embodiment of a sensor of the invention for use in a device of the type described in document EP-A-544 583 is shown in Figures 4a and 4b.
  • Figure 4a is a side view of the device, while Figure 4b shows half of it in a perspective view.
  • the sensor or the sensor element shown has an outside surface constituted firstly by conductive portions 36-1, ..., 36-6, 37-1, ..., 37-6, and insulating portions 42 which are formed respectively of a material that is hard and electrically conductive and of a material that is hard and electrically insulating, said materials being deposited in the form of layers.
  • the layers are preferably deposited on a substrate in the form of a sector of a cylinder.
  • the cylinder sector is in fact a half-cylinder, so a sensor is built up from two sensor elements.
  • the element When the invention is applied to making a sensor element of the type shown in Figures 1a and 1b, then, in the same manner, the element presents an outside surface made up of conductive portions and of insulating portions respectively made of materials that are hard and electrically conductive, and hard and electrically insulating.
  • the conductive and insulating portions are then distributed in a given pattern that is different from the pattern shown in Figure 4a, and that corresponds to the pattern of Figure 1b. In this case, the cylindrical sector also extends over an angle of about 72°.
  • the sensor element of Figure 4a comprises a support or substrate 34 made of metal, e.g. a 316-L type stainless steel, electrodes 36-1, 36-2, ..., 36-6 for injecting current, and monitoring electrodes 37-1, ..., 37-6 that are elongate in shape parallel to an axis XX' of circular symmetry of the metal support 34, and insulated from the current injection electrodes.
  • Two annular monitoring electrodes 38 and 40 are disposed around the support 34.
  • connection means constituted by connection tabs 46-1, 46-2, ..., 46-6 and 50-1, 50-2, ..., 50-6 and by electrical link elements 48-1, ..., 48-6 serve to connect the current injection electrodes 36-1, ..., 36-6 to an external current feed (not shown) via connection means 58 (referred to below as the "through connection") disposed on the inside or against the inside surface of the support 34 and described in greater detail below. Only one through connection is shown in Figure 4a.
  • the monitoring electrodes 37-1, ..., 37-6 are connected to electrical outlets or to voltage measuring means (not shown) via through connection means 52-1, ..., 52-6; 54-1, ..., 54-6; and 56-1, ..., 56-6.
  • the electrical link elements such as the elements 48 may be conductive tracks, e.g. made of nickel or of copper, of the type used in printed circuit technology.
  • the elements 48 may also be electric wires.
  • Conductive tracks 49, 51 connect the monitoring electrodes 39, 40 to voltage measuring means via the through connection 58.
  • a second layer 60 of a material that is hard and electrically insulating covers the entire assembly with the exception of zones that correspond to the electrodes (36-1, ..., 36-6, 37-1, ..., 37-6).
  • the second layer 60 may be of limited extent, so as to avoid covering the electrical link elements 48-1, ..., 48-6, 54-1, ..., 54-6, extending a little way on either side of these elements.
  • the materials of the layers 42 and 60 may be selected from oxides such as SiO 2 , TiO 2 , Al 2 O 3 , ZrO 2 , Cr 2 O 3 , and Y 2 O 3 which have very good properties of hardness and resistance to corrosion and to wear.
  • the material from which the conductive zones 36 and 37 is made may be of the carbide type (B 4 C, SiC, Be 2 C, TiC, WC, TaC, NbC, Cr 3 C 2 , b-Mo 2 C, h-MoC, VC, HfC, ZrC), optionally doped, e.g. with cobalt, nickel, chromium, or a ternary mixture such as nickel-chromium-molybdenum (NiCrMo).
  • the carbide type B 4 C, SiC, Be 2 C, TiC, WC, TaC, NbC, Cr 3 C 2 , b-Mo 2 C, h-MoC, VC, HfC, ZrC
  • cobalt nickel, chromium, or a ternary mixture such as nickel-chromium-molybdenum (NiCrMo).
  • the bonding layer 45 In order to enhance bonding of the first layer 42 of hard and insulating material on the substrate 34, it is possible to deposit a bonding layer 45 directly onto the substrate 34 before depositing the layer 42 (where the bonding layer is shown as a dashed line in Figure 4b), the bonding layer being made of a material such as MCrAlY where M is a metal such as nickel (Ni) or a material such as NiAl, or else molybdenum.
  • This bonding layer also makes it possible:
  • NiCrAlY has the property of developing a ceramic lattice in its bulk, when it is in oxidizing conditions. This enhances bonding of coatings constituted by oxides and/or carbide, in particular in conditions of a highly corrosive atmosphere.
  • the various materials are chosen as a function of the stresses imposed while the device is in use, and in particular stresses that are mechanical, thermal, and chemical.
  • Table I gives the corresponding hardness in N/mm 2 , and also the thermal expansion coefficient.
  • Material Hardness (N/mm 2 ) Thermal expansion coefficient (x 10 -6 /°C)
  • Tension tests have been performed that enable comparisons to be made between the tensile properties of a steel (316-L type stainless steel) without any layer of hard material and the properties of the same steel when coated in a layer of tungsten carbide doped with cobalt CW(Co) or in a layer of chromium trioxide Cr 2 O 3 .
  • references 62 and 64 designate respectively the steel substrate and the deposited layer of carbide or of oxide.
  • the effect of the coatings is to divide the elongation of the substrate by a factor of about 1.2, and to improve the elastic limit of the substrate.
  • the coating is made of Cr 2 O 3 , the value of the breaking load is lower than in the absence of the coating. Nevertheless, it can be concluded from these values that the overall mechanical qualities of the device are improved by the presence of a substrate.
  • the first column gives final roughness R a (in ⁇ m); the second and third columns give the starting and average coefficients of friction during the test; the fourth column gives the volume worn away (in mm 3 ); the fifth column gives wear rate (in mm3/Nm); and the sixth column gives the wear (in mg) of the alumina sphere.
  • Table IV shows the improvement obtained on going from a substrate without coating to a substrate with a coating, whether in terms of final roughness, worn volume, rate of wear, or wear of the sphere.
  • the apparatus for performing these tests is shown diagrammatically in Figure 7a.
  • the rectangular shape of the electrolyte bath 86 tends to ensure current lines that are rectilinear, and it is thus possible to establish equipotential lines (which are perpendicular to the current lines).
  • References 70, 76, and 78 designate respectively the test electrode, the reference electrode, and the counter-electrode.
  • the three electrodes 70, 76, and 78 are coupled to an electrochemical interface 72 and to a frequency analyzer 74.
  • Tests were performed using tungsten carbide (CW) and various dopings of cobalt, nickel, or of the Ni + refractory type (e.g. NiCrMo).
  • the tests with cobalt doping were performed using a reference electrode made of 316-L stainless steel, while the other tests were made with a reference electrode made of platinum. Additional tests using a platinum reference electrode and cobalt doping at 12% and at 100% have served to demonstrate that the choice of reference electrode does not alter the result.
  • the contact impedances for various dopings and at two working frequencies (10 Hz and 100 Hz) are given in Table V.
  • Contact impedance is the same for identical doping percentage, regardless of whether the doping uses cobalt or nickel.
  • the CW(NiCrMo) coating has the lowest contact impedance above 10 Hz.
  • a first technique is chemical vapor deposition (CVD). It also covers variants thereof such as plasma-enhanced chemical vapor deposition (PECVD), low pressure chemical vapor deposition (LPCVD), photo-assisted chemical vapor deposition (PCVD) and laser-assisted chemical vapor deposition (LCVD).
  • PECVD plasma-enhanced chemical vapor deposition
  • LPCVD low pressure chemical vapor deposition
  • PCVD photo-assisted chemical vapor deposition
  • LCD laser-assisted chemical vapor deposition
  • the advantage of this technique lies in the possibility of producing layers that are uniform, compact, and that bond very strongly. At low temperature and at high concentration, it is possible to produce coatings that are fine or amorphous.
  • the disadvantage of this technique is the need to operate at high temperature (700°C - 1000°C) which can give rise to damage to the substrate or which can cause undesirable mechanical properties to be developed therein.
  • PVD physical vapor deposition
  • Hybrid methods combining chemical and physical methods of forming the solid deposit may also be used in order to prepare coatings that are hard and withstand wear, such as the coatings described above.
  • Another method is laser deposition. This method uses a laser beam which provides the activation energy required for a chemical reaction. A laser beam can also be used in combination with the CVD method, to provide an external energy source. It is then possible to deposit fine structures with great accuracy.
  • sol-gel method Another method is the sol-gel method.
  • a solution of the elements that are to be deposited is formed in an organic solvent, and the solution is then polymerized to form a gel which is applied in the desired shape on the substrate.
  • the gel is finally dried and baked to eliminate the organic solvent, thereby forming the desired final solid phase.
  • ion implantation Another technique is ion implantation. This technique which is extremely effective for treating surfaces makes use of high energy ions to modify the properties or the composition of a surface.
  • the ions from a given ion source are accelerated (with a voltage of 10 kV to 100 kV) and they bombard a target which may be rotated in order to obtain a coating that is uniform. Deposits are thus obtained that bond strongly to the substrate and that are coherent.
  • the material that is to be deposited is melted and the resulting droplets are sprayed against the substrate at high speed (about 300 meters per second (m/s)).
  • the substrate is generally kept at a temperature below 150°C. It is thus possible to obtain coatings on substrates that have a low melting temperature (aluminum alloy, stainless steel, plastics).
  • the temperature at the outlet from the plasma torch is extremely high (typically 7,000°C to 10,000°C), which means that it is necessary to use powders that have high melting points.
  • the plasma is formed using a gas such as argon, helium, nitrogen, or oxygen, or mixtures thereof.
  • argon is that it is easily ionized and it makes it possible to produce a plasma that is more stable at torch operating voltages of about 70 volts.
  • the grains of material that are injected at the end of the torch melt into droplets which, on impact against the substrate, take up the shape of disks or platelets. The impact is exothermal.
  • the density of the deposited layer increases with the fluidity of the droplets and with their impact speed.
  • This method is particularly well adapted to depositing the hard materials concerned by the present invention, whether they are insulating or electrically conductive.
  • the equipment described in patent application EP-A-0 580 097 published on January 26, 1994 can be used for implementing the method.
  • the manufacture of a sensor of the invention will make use, for example, of various different plasma spraying steps for materials that are hard and insulating and for materials that are hard and conductive, e.g. onto a support or substrate that is in the form of a sector of a cylinder.
  • Predetermined patterns in the distribution of the conductive portions and the insulating portions can be achieved by successive masks, e.g. using masks made of metal.
  • the first step consists in choosing an appropriate substrate, in this case a half-tube 34 of a stainless steel that is poorly magnetizable, e.g. 316-L type stainless steel.
  • the substrate is machined so as to be capable of receiving the desired through connection 58 (through connections are described in detail below). It is degreased using trichloroethylene vapor and it is then subjected to corundum blasting (30 grade) at a pressure of 2 bars.
  • a bonding layer 45 of NiCrAlY is deposited to a thickness of about 50 ⁇ m by plasma spraying.
  • plasma spraying is used to deposit a layer 42 of Al 2 O 3 -TiO 2 (97%-3%) to a thickness of about 250 ⁇ m over the entire part except in the two zones for grounding electrodes ( Figure 9a, references 90 and 92).
  • a metal mask with cutouts is put into place to enable the "printed circuit” that forms the electrical link means 48-1, ..., 48-6, 54-1, ..., 54-6, 49, and 51 to be sprayed.
  • the printed circuit which is made of nickel (or copper or aluminum) is sprayed to a thickness of about 150 ⁇ m.
  • Each of the two ends 46-1, ..., 46-6, 50-1, ..., 50-6, 52-1, ..., 52-6, 56-1, ..., 56-6 of each printed circuit element is then masked (see Figure 9c) and a layer of Al 2 O 3 -TiO 2 is sprayed to a thickness of 400 ⁇ m.
  • the surface is masked in part so as to spray on the electrodes of tungsten carbide (CW) 17% doped with Co, to a thickness of about 200 ⁇ m.
  • CW tungsten carbide
  • These electrodes are referenced 37-1, ..., 37-6 and 36-1, ..., 36-6 in Figure 9d.
  • each end of the printed circuit is grooved adjacent to the through connection 58 over a width of 0.2 mm.
  • the nickel or copper wires having a diameter of 0.2 mm are then mounted in the grooves.
  • the gaps between the through connections are masked.
  • the wires are stuck to the through connection by spraying on nickel to a thickness of about 150 ⁇ m.
  • the through connection zones are then insulated by spraying on Al 2 O 3 to a thickness of about 300 ⁇ m.
  • a final treatment serves to reduce the porosity of the outermost layers.
  • This treatment may consist in:
  • all of the layers are deposited by plasma spraying using a plasma torch, and at each step, it is possible to monitor the appearance and the thickness of the deposits being made. Similarly, it is easy to monitor the insulation (or conductivity as the case may be) of the deposited insulating layers (or conductive layers).
  • This method makes use of conventional masking techniques as used in the printed circuit field, in association with the plasma spraying technique which is, itself, well mastered and cheap.
  • masking purposes it is also possible to use "silkscreen" type techniques, where the mask is constituted by a substance that adheres to the substrate, and that is removed after spraying. It is thus possible to provide a sensor that is easy to manufacture, low in cost, and easily reproducible.
  • the method as described above enables layers to be deposited in uniform manner on a surface that is itself uniform and that has previously been cleaned or degreased.
  • the particles constituting the coating 42 are sprayed onto the substrate (e.g. by plasma spraying), bonding is essentially mechanical, the particles literally called “hooking" themselves onto the roughnesses of the spray-receiving surface. Consequently, prior to deposition of the bonding layer, the substrate may advantageously be roughened by sand blasting.
  • Figure 10a is a perspective view of a half-cylinder 94 which is used as the substrate for the various deposits (deposit of insulating material, deposit of conducting material, connection tracks).
  • the substrate 94 is etched, e.g. to have the shapes which it is desired to impart to the conductive zones and/or to the connection tracks.
  • Figure 10b shows a portion of the section of the substrate on plane P of Figure 10a, which portion is to have the tracks 96 and 98 deposited therein, Figure 10b being prior to any deposition.
  • References 100 and 102 designate etched zones that extend parallel to the axis XX' of the cylinder.
  • Etching may be to a depth e lying in the range a few tens of micrometers to a few hundreds of micrometers.
  • a first layer 104 is deposited (e.g. a layer of hard insulating material such as an Al 2 O 3 -TiO 2 mixture). This deposition can be performed by any one of the techniques mentioned above, and is preferably performed by plasma spraying. It is thus possible to deposit a layer 104 whose thickness lies in the range a few tens of micrometers to a few hundreds of micrometers. The outside surface of this layer 104 is undulating, having valleys 106 and 108 in alignment with the etched zones 100 and 102.
  • a layer 110 is deposited of a material that is hard and electrically conductive, e.g. cobalt-doped tungsten carbide.
  • This layer 110 is also shaped in a manner that corresponds to the etched zones 100 and 102.
  • the next step consists in rectifying the assembly so as to allow the conductive zones 96 and 98 to remain only in the valleys 106 and 108 defined by the layer 104. Thereafter, it is naturally possible to deposit a uniform layer of material that is hard and electrically insulating over the entire assembly.
  • the above-described variant method of making the conductive connection tracks can be adapted to making conductive zones similar to the zones 36-1, ..., 36-6, 37-1, ..., 37-6 in Figure 4a. It can easily be combined with the technique of selective deposition using masks, as described above.
  • the various sensors and methods of manufacturing them as described above thus present numerous advantages over devices and methods of the prior art.
  • the coatings enable the entire device to have great mechanical strength imparted thereto, and in particular there is no longer any risk of unseating as in the case shown in Figure 1b.
  • the chosen coatings have good chemical resistance and it is possible to modulate the contact impedance as a function of the deposits made.
  • the methods described are easy to implement, and they are easy to modulate (if the plasma spraying technique is being used, it is possible to vary the composition of the deposited layers by appropriate mixing of the powders that are being sprayed).
  • the resulting device presents far fewer different components since the prior art device requires, as already explained in the introduction, electrodes, a rubber coating, and wire connections. In this case, all of those elements have been replaced by layers that can be deposited on the substrate using a single technique.
  • Figure 11 shows the noise value for each channel of the prior art electrode (points marked by crosses in Figure 11), and the noise level for each channel of the device of the present invention (marked by circles in Figure 11). It can be seen that for most of the electrodes, the noise value is smaller for the sensor of the invention than for the sensor of the prior art. With the invention, it has been possible to improve the signal-to-noise ratio by a factor of four.
  • the sensor of the invention as described above can be used in combination with a through connection of the prior art.
  • a through connection is shown diagrammatically in Figure 3b, where reference 39 designates a metal base welded against the inside face of the substrate 23, said metal base generally being embedded in a rubber molding (not shown in Figure 3b); it is extended by a connector 41 of stainless steel.
  • Figure 12 is a perspective view of a support 114 on which layers of conductive material forming the electrodes and the conductive tracks are to be deposited, the section passing through the through connection that is referenced 118.
  • the substrate 114 of thickness e must initially be milled to form a hole 116 in the form of a truncated cone. Relative to the inside surface 120 of the support, the walls of the truncated cone form an angle ⁇ .
  • the through connection is essentially constituted by a truncated cone 122 of height h which is greater than or equal to the thickness e of the substrate 114 and which has an angle at the apex that is substantially equal to 2 ⁇ .
  • the cone 122 is made of a metal, e.g.
  • the conductor wires 132-n serve to provide electrical connection with the conductive tracks 134-1, ..., 134-6 deposited on the outside surface of the substrate 114 (here again only six conductive tracks are mentioned; it will be quite possible to use 12 or 24 conductive tracks, as in Figures 4a or 4b).
  • the connections 133-n serve to provide respective electrical links with the power supplies or the measurement apparatuses that are contained in the logging string having the device situated at its end.
  • Figures 13a to 13d show the steps in a method of depositing the set of elements 126-1, 128-1, and 130-1 in a groove 124-1.
  • a layer 136 of insulating material is deposited on the bottom and on the sides of the groove 124-1.
  • the layer 136 may be constituted by A1203 deposited by plasma spraying.
  • the layer 136 retains the shape of a groove and is capable, in a second step ( Figure 13b) of receiving a deposit of a conductive material 138, e.g. by plasma spraying.
  • the third step is a machining step ( Figure 13c) serving to reduce the thickness of the layers of insulator and conductor deposited during the preceding steps to a value that is smaller than the depth of the groove 124-1. This defines the final shape of the element 126-1 situated in the bottom of the groove 124-1 and of the conductive element 128-1.
  • the last layer 140 of insulating material then needs to be deposited ( Figure 13d), preferably using the same technique as that used for depositing the layer 138.
  • a final rectification step serves to bring down the level of said layer 140 to that of the layer 130-1 which is flush with the outside surface of the truncated cone 122.
  • the connection wires 132-1 and 133-1 are fixed, e.g. by brazing.
  • a layer 126-1 of insulating material is deposited so that it matches the shape of the groove.
  • a conductor wire 144-1 is then put into place and covered in a layer 146 of insulating material, after which it is rectified so as to obtain a layer 130-1 that is flush with the outside surface of the truncated cone 122.
  • FIG. 15 A variant of this type of through connection is shown in Figure 15 where the truncated cone 148 is seen from above.
  • the truncated cone has exactly the same shape as the cone 122 shown in Figure 12 and it has grooves 150-1, ..., 150-6. However, it is not made of steel, but of ceramic. It is therefore possible to place a conductive element, e.g. a conductor wire 152-n, directly on the bottom of each groove 150-n without previously depositing a layer of insulating material. Thereafter, the conductive element is covered in a layer 154-n of insulating material whose outside surface can be rectified. The conductor wires 132-n, 133-n can then be brazed to the ends of the conductor wires 154-n.
  • a conductive element e.g. a conductor wire 152-n
  • this through connection is easier and cheaper to make than are prior art through connections.
  • the steps of welding and of molding in rubber are avoided, and the various deposits made in the grooves can be implemented using the techniques that are described above for making deposits on the outside of the substrate, and in particular the technique of deposition by plasma spraying.
  • this type of through connection provides sealing between the outside and the inside of the substrate, particularly when the angle at the apex 2 ⁇ of the truncated cone 122 lies in the range 15° to 35°. Sealing can be even further improved if, after the various layers have been deposited in the grooves, a layer of copper or of silver is deposited to a thickness of a few micrometers on the outside surface of the truncated cone.
  • FIG. 16 is a side view of a substrate 164 shown in section through the through connection given reference 168.
  • the substrate is initially milled so as to provide an opening having two portions.
  • a first portion 170 is in the form of a truncated cone. Its larger base faces towards the outside surface of the substrate 164 and its walls are inclined at an angle ⁇ relative to said outside surface.
  • the truncated cone is continued by a cylindrical opening 166 which constitutes the second portion of the opening.
  • the diameter of the cylindrical opening is less than the diameter of the truncated cone section 170.
  • Various layers are then deposited on the substrate 164, e.g.
  • the tracks 174 and 176 are extended by fixing conductor elements 180, 182 to their ends, e.g. by brazing, with the elements being connected at their opposite ends to a connector 184 fixed against the inside face of the substrate 164, e.g. by welding or by bolting.
  • the two openings 170 and 166 are then filled with a resin 185 or with an adhesive that is insulating and not permeable to water.
  • the angle ⁇ is preferably chosen to lie in the range 20° to 45°, thereby enabling good sealing and good mechanical resistance to external pressure to be achieved.
  • the angle ⁇ is preferably substantially equal to 30°.
  • FIGS. 17a and 17b are a section view and a side view of a substrate 194 through its through connection which is referenced 198.
  • the substrate 194 is initially milled so as to provide a circular opening 192 adjacent to its outside surface, which opening is extended inwards by a substantially frustoconical opening 193.
  • a layer 196 of hard and insulating material is then deposited with or without a bonding layer. This insulating layer is extended inside the hole constituted by the openings 192 and 193 all the way to the inside surface of the substrate 194.
  • Conductive tracks 198 and 200 are deposited on this layer and to the outside, and they are connected at their ends closest to the opening 192 to respective conductor wires 202, 204.
  • the wires are brought towards the inside surface of the substrate 194 where they are fixed at their respective ends 206, 208 by means of a layer of insulating material 210, 212 which may be deposited using the same technique as that used for making the deposits on the outside surface of the substrate 194.
  • a second layer 214 of hard and insulating material is deposited. Thereafter, the inside of the openings 192, 193 is filled with an epoxy resin 195.
  • Filling is performed in such a manner that the free surface 197 of the resin on the inside of the substrate 194 leaves portions 216, 218 of the conductor wires 202, 204 uncovered in the vicinity of the ends 206, 208 of these wires. These are the portions that serve to provide contacts with a conventional connector applied to the inside surface of the substrate 194 and pressed thereagainst.
  • the inside surface of the substrate 194 is rectified.
  • This rectified zone 220 must be wide enough to receive a connector 222.
  • the structure of the deposited layers is then identical to that described above with reference to Figure 17a except that the layers 210, 212 of insulating material are now extended towards the inside of the frustoconical opening 193.
  • the openings 192 and 193 are then filled with resin 195 so that the surface 199 of the resin on the inside of the substrate leaves uncovered portions 226, 228 of the conductors 202, 204 along the sloping wall of the frustoconical opening 193.
  • the connector may be pressed against the rectified zone 220 of the inside surface of the substrate 194 by being bolted or clamped against said surface.
  • An 0-ring 234 may be provided to ensure sealing when the connector 222 is put into place against the rectified zone 220.
  • the resin may be such as to compress under pressure while still ensuring sealing and insulation.
  • the openings 192 and 193 may be of very small diameter, being just large enough to pass through the conductors 202, 204.
  • the conductor wires then extend along the inside surface of the substrate 154, e.g. in the form of electrical links which are deposited using the same techniques as are used for the electrical links situated on the outside surface of the substrate, thereby serving to reach a connector such as the connector 222 of Figure 17b.

Landscapes

  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Geology (AREA)
  • Remote Sensing (AREA)
  • Physics & Mathematics (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Geophysics (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
  • Testing Or Calibration Of Command Recording Devices (AREA)
  • Semiconductor Lasers (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
EP95402667A 1994-11-29 1995-11-27 An electrical logging sensor and its method of manufacture Expired - Lifetime EP0715187B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9414291A FR2727464A1 (fr) 1994-11-29 1994-11-29 Capteur de diagraphie electrique et son procede de realisation
FR9414291 1994-11-29

Publications (2)

Publication Number Publication Date
EP0715187A1 EP0715187A1 (en) 1996-06-05
EP0715187B1 true EP0715187B1 (en) 2001-07-18

Family

ID=9469257

Family Applications (1)

Application Number Title Priority Date Filing Date
EP95402667A Expired - Lifetime EP0715187B1 (en) 1994-11-29 1995-11-27 An electrical logging sensor and its method of manufacture

Country Status (6)

Country Link
US (1) US5721492A (ru)
EP (1) EP0715187B1 (ru)
AU (1) AU707250B2 (ru)
CA (1) CA2163957A1 (ru)
DE (1) DE69521771T2 (ru)
FR (1) FR2727464A1 (ru)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7819181B2 (en) 2003-07-25 2010-10-26 Schlumberger Technology Corporation Method and an apparatus for evaluating a geometry of a hydraulic fracture in a rock formation

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040252748A1 (en) * 2003-06-13 2004-12-16 Gleitman Daniel D. Fiber optic sensing systems and methods
CN101928931A (zh) * 2009-06-18 2010-12-29 鸿富锦精密工业（深圳）有限公司 镀膜装置及方法
US9677394B2 (en) 2013-06-28 2017-06-13 Schlumberger Technology Corporation Downhole fluid sensor with conductive shield and method of using same
WO2017116499A1 (en) * 2015-12-28 2017-07-06 The Trustees Of Princeton University Elastic filament velocity sensor

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FR327422A (fr) * 1902-12-16 1903-06-22 Fulcher William Henry Perfectionnements aux appareils excavateurs
US3072843A (en) * 1957-08-13 1963-01-08 Texaco Inc Abrasion resistant coating suitable for borehole drilling apparatus
US3268801A (en) * 1963-04-30 1966-08-23 Texaco Inc Apparatus having a pair of spaced electrodes for measuring spontaneous potentials in a well bore while drilling
US3388325A (en) * 1966-02-23 1968-06-11 Schlumberger Well Surv Corp Apparatus for supplying an equal potential to circumferential portions of a circumferentially extending electrode
US4602690A (en) * 1980-12-11 1986-07-29 Exxon Production Research Co. Detachable apparatus for preventing differential pressure sticking in wells
US4618828A (en) * 1982-11-12 1986-10-21 Teleco Oilfield Services Inc. Insulating segment for a drill string electrode structure
US4666733A (en) * 1985-09-17 1987-05-19 Electric Power Research Institute Method of heat treating of wear resistant coatings and compositions useful therefor
FR2626380B1 (fr) * 1988-01-22 1990-05-18 Inst Francais Du Petrole Interpretation de diagraphies electriques
FR2643465B1 (fr) 1989-02-20 1991-05-24 Schlumberger Prospection Procede et dispositif pour mesurer la resistivite des formations geologiques
US4997044A (en) * 1989-12-01 1991-03-05 Stack Walter E Apparatus for generating hydraulic shock waves in a well
GB2253908B (en) * 1991-03-21 1995-04-05 Halliburton Logging Services Apparatus for electrically investigating a medium
US5235285A (en) * 1991-10-31 1993-08-10 Schlumberger Technology Corporation Well logging apparatus having toroidal induction antenna for measuring, while drilling, resistivity of earth formations
FR2684453B1 (fr) * 1991-11-28 1994-03-11 Schlumberger Services Petroliers Procede et dispositif de diagraphie a electrodes annulaires et azimutales.
US5320879A (en) 1992-07-20 1994-06-14 Hughes Missile Systems Co. Method of forming coatings by plasma spraying magnetic-cerment dielectric composite particles

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7819181B2 (en) 2003-07-25 2010-10-26 Schlumberger Technology Corporation Method and an apparatus for evaluating a geometry of a hydraulic fracture in a rock formation

Also Published As

Publication number Publication date
EP0715187A1 (en) 1996-06-05
DE69521771T2 (de) 2002-05-23
DE69521771D1 (de) 2001-08-23
US5721492A (en) 1998-02-24
FR2727464B1 (ru) 1997-02-07
AU707250B2 (en) 1999-07-08
AU3909795A (en) 1996-06-06
FR2727464A1 (fr) 1996-05-31
CA2163957A1 (en) 1996-05-30

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